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Ecology and Epidemiology

Whitefly-borne Viruses of Melons and Lettuce in Arizona. J. K. Brown, Department of Plant Pathology, University of Arizona, Tucson, 85721; M. R. Nelson, Department of Plant Pathology, University of Arizona, Tucson, 85721. Phytopathology 76:236-239. Accepted for publication 12 September 1985. Copyright 1986 The American Phytopathological Society. DOI: 10.1094/Phyto-76-236.

Two distinct whitefly (Bemisia tabaci)-transmitted viruses were isolated from row crops in Arizona. Long, flexuous rods (10-12 x 1,200-2,000 nm) associated with melons and lettuce, and geminiviruslike particles (18 x 30 nm) associated exclusively with melons were observed by electron microscopy in extracts of infected plants. The flexuous rod-shaped virus incited severe foliar yellowing or reddening, and stunting in infected plants and is whitefly transmissible but not mechanically transmissible. These characteristics are like those described for the lettuce infectious yellows virus. The geminivirus incited leaf curling, vein-banding, mottling, and stunting in infected plants and is both whitefly transmissible and mechanically transmissible. The geminivirus from Arizona appears to be distinct from squash leaf curl virus (SLCV) based upon differences in symptomatology, host range, and mechanical transmissibility, and it is tentatively designated as watermelon curly mottle virus (WCMoV).